Showing papers by "University of Madras published in 2009"

Mycobased synthesis of silver nanoparticles and their incorporation into sodium alginate films for vegetable and fruit preservation.

Abstract: Biosynthesis of silver nanoparticles using Trichoderma viride and their incorporation into sodium alginate for vegetable and fruit preservation has been demonstrated in this study. Aqueous silver (Ag(+)) ions when exposed to the filtrate of T. viride are reduced in solution. These extremely stable silver nanoparticles were characterized by means of UV-vis spectrophotometer, FTIR, TEM, and EDS. The nanoparticles exhibit maximum absorbance at 421 nm in the UV spectrum. The presence of proteins was identified by FTIR. TEM micrograph revealed the formation of polydispersed nanoparticles, and the presence of elemental silver was confirmed by EDS analysis. The silver nanoparticle incorporated sodium alginate thin film shows good antibacterial activity against test strains. This film increases the shelf life of carrot and pear when compared to control with respect to weight loss and soluble protein content. These results show silver nanoparticle incorporated sodium alginate coated vegetables and fruits are suitable for preservation.

Phyllanthin-assisted biosynthesis of silver and gold nanoparticles: a novel biological approach

Abstract: The anisotropic gold and spherical–quasi-spherical silver nanoparticles (NPs) were synthesized by reducing aqueous chloroauric acid (HAuCl4) and silver nitrate (AgNO3) solution with the extract of phyllanthin at room temperature. The rate of reduction of HAuCl4 is greater than the AgNO3 at constant amount of phyllanthin extract. The size and shape of the NPs can be controlled by varying the concentration of phyllanthin extract and thereby to tune their optical properties in the near-infrared region of the electromagnetic spectrum. The case of low concentration of extract with HAuCl4 offers slow reduction rate along with the aid of electron-donating group containing extract leads to formation of hexagonal- or triangular-shaped gold NPs. Transmission electron microscopy (TEM) analysis revealed that the shape changes on the gold NPs from hexagonal to spherical particles with increasing initial concentration of phyllanthin extract. The Fourier transform infrared spectroscopy and thermogravimetric analyses reveal that the interaction between NPs and phyllanthin extract. The cyclic voltammograms of silver and gold NPs confirms the conversion of higher oxidation state to zero oxidation state. Anisotropic gold and silver nanoparticles were synthesized by a simple procedure using phyllanthin extract as reducing agent. The rate of bioreduction of AgNO3 is lower than the HAuCl4 at constant concentration of phyllanthin extract. The required size of the nanoparticles can be prepared by varying the concentration of phyllanthin with AgNO3 and HAuCl4.

Screening of marine actinomycetes isolated from the Bay of Bengal, India for antimicrobial activity and industrial enzymes

Abstract: A total of 288 marine samples were collected from different locations of the Bay of Bengal starting from Pulicat lake to Kanyakumari, and 208 isolates of marine actinomycetes were isolated using starch casein agar medium. The growth pattern, mycelial coloration, production of exopolysaccharides and diffusible pigment and abundance of Streptomyces spp. were documented. Among marine actinomycetes, Streptomyces spp. were present in large proportion (88%). Among 208 marine actinomycetes, 111 isolates exhibited antimicrobial activity against human pathogens, and 151 showed antifungal activity against two plant pathogens. Among 208 isolates, 183, 157, 116, 72 and 68 isolates produced lipase, caseinase, gelatinase, cellulase and amylase, respectively. The results of diversity, antimicrobial activity and enzymes production have increased the scope of finding industrially important marine actinomycetes from the Bay of Bengal and these organisms could be vital sources for the discovery of industrially useful molecules/enzymes.

Assessment of groundwater quality and hydrogeochemistry of Manimuktha River basin, Tamil Nadu, India

Abstract: Groundwater quality assessment study was carried out around Manimuktha river basin, Tamil Nadu, India. Twenty six bore well samples were analyzed for geochemical variations and quality of groundwater. Four major hydrochemical facies (Ca–HCO3, Na–Cl, Mixed CaNaHCO3, and mixed CaMgCl) were identified using a Piper trilinear diagram. Comparison of geochemical results with World Health Organization, United States Environmental Protection Agency, and Indian Standard Institution drinking water standards shows that all groundwater samples except few are suitable for drinking and irrigation purposes. The major groundwater pollutions are nitrate and phosphate ions due to sewage effluents and fertilizer applications. The study reveals that the groundwater quality changed due to anthropogenic and natural influence such as agricultural, natural weathering process.

Study of hydrogen bonds in amino acids and peptides.

Abstract: An analysis of the various parameters associated with N-H… O type of hydrogen bonds has been made using data from reported crystal structures of amino acids and simple peptides. The different parameters at the donor and the acceptor ends have been suitably defined and evaluated. In some cases the analysis is done depending upon the chargedness or other characteristics of the donor and acceptor groups. Histograms giving the distribution of these parameters have been drawn and possible conclusions arrived at: 1. The distribution shows a maximum between 2.8 A and 2.9 A for the charged donor group and 2.9 A and 3.0 A for the uncharged donor group and is probably not dependent upon the charge on the acceptor group. 2. The angle between the directions CO and O. N tends to lie between two cones about C O with semi-vertical angles 40 and 70°. The orientation of the directions O. N and O. H with respect to the lone pair orbital directions on the acceptor oxygen atoms are analysed in detail using spherical polar coordinates. The analysis indicates that the group NH has a very strong tendency to point towards the acceptor oxygen atom. A general feature has been found in that the direction N-H tends to be closer to an orbital if the oxygen is an acceptor of two hydrogen bonds, while the direction tends to lie in between the orbitals when the acceptor oxygen is the receipient of only one hydrogen bond. The possible explanation of this on the basis of lone pair interaction is briefly discussed.

Studies on the conformation of amino acids. VI. Conformation of the proline ring as observed in crystal structures of amino acids and peptides.

Abstract: The paper deals with an analysis of the available crystal structure data related to proline compounds so as to obtain information about bond lengths, bond angles, and the conformation of the pyrrolidine ring. The interesting results are: 1. The atoms Cβ, Cα, N, and Cs are nearly coplanar, with the torsion angle 0 about the Cα - N bond varying from about -15° to -15°. The Cγ atom is displaced from this plane, either up or down, so that the ring exists in one of the two puckered conformations, designated A and B. Conformation A is characterized by negative and may be termed Cγ-exo when referred to the displacement of the carbonyl carbon C. Conformation B has positive x l and is Cγ-endo; Cγ-exo is slightly preferred over C-endo, although both conformations occur simultaneously in some crystal structures with partial probabilities. In the other structures, the non-occurring position for C y is found to be disallowed by intermolecular contacts. The proline conformations observed correspond to the 'envelope' type of conformation of the cyclopentane ring. In peptides, the three bonds at N are nearly coplanar, and the torsion about N- Cα bond is nearly - 60°. 2. The observed ranges of (x 1 , x 2 , x 3 , x 4 ) are (0 to –30°, 15 to 50°, –15 to - -30°, 5 to 25°) for conformation A and (20 to 35 0 , -30 to - 40 0 , 20 to 35°, 5 to -20°) for conformation B; for θ and φ the ranges are -15° to -15°, -45 to -75°. The bond lengths and bond angles are not influenced by the conformation of the ring, unlike ribose.

Best Proximity Point Theorems for p-Cyclic Meir-Keeler Contractions

Abstract: We consider a contraction map of the Meir-Keeler type on the union of p subsets , , of a metric space ( ) to itself. We give sufficient conditions for the existence and convergence of a best proximity point for such a map.

Antioxidant and anticancer efficacy of hesperidin in benzo(a)pyrene induced lung carcinogenesis in mice

Abstract: Chemoprevention is regarded as one of the most promising and realistic approaches in the prevention of cancer. Several bioactive compounds present in fruits and vegetables have revealed their cancer curative potential on lung cancer. Hesperidin is one such naturally occurring flavonoid widely found in citrus fruits. The aim of the present study is to divulge the chemopreventive nature of hesperidin during benzo(a)pyrene (B(a)P) induced lung cancer in Swiss albino mice. Administration of B(a)P (50 mg/kg body weight) to mice resulted in increased lipid peroxides (LPO), lung specific tumor marker carcinoembryonic antigen (CEA) and serum marker enzymes aryl hydrocarbon hydroxylase (AHH), gamma glutamyl transpeptidase (GGT), 5'nucleotidase (5'ND) and lactate dehydrogenase (LDH) with concomitant decrease in the levels of tissue antioxidants like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), vitamin E and vitamin C. Hesperidin supplementation (25 mg/kg body weight) significantly attenuated these alterations thereby showing potent anticancer effect in lung cancer. Further the antiproliferative effect of hesperidin was confirmed by histopathological analysis and proliferating cell nuclear antigen (PCNA) immunostaining. Overall, these findings substantiate the chemopreventive potential of hesperidin against chemically induced lung cancer in mice.

Taxol production by Pestalotiopsis terminaliae, an endophytic fungus of Terminalia arjuna (arjun tree).

Abstract: Terminalia arjuna is a medicinal plant (the arjun tree) that possesses anticancer activity. An endophytic fungus, Pestalotiopsis terminaliae, was isolated from the fresh healthy leaves of this tree and was screened for the production of taxol, an anticancer drug, in artificial culture medium. The taxol produced was analysed chromatographically and spectrometrically. The amount of taxol produced by the fungus was found to be 211.1 microg/litre. This was sufficient for the fungus to be considered as a potential source material for improvement, by engineering, the production of taxol. The fungal taxol extracted from an organic extract of the fungal culture had strong cytotoxic activity towards BT220, H116, Int 407, HL 251 and HLK 210 human cancer cells in vitro when tested using an apoptosis assay.

Antihyperglycemic Effect of Mangiferin in Streptozotocin Induced Diabetic Rats

Abstract: The study was undertaken to evaluate the antihyperglycemic potential of mangiferin purified from methanolic root extract of Salacia chinensis (S. chinensis )i nc ontrol and streptozotocin (STZ)-induced diabetic rats. The mangiferin was administered orally at a dose of 40 mg/kg weight per day (30 days) to STZ-induced diabetic rats. The mangiferin treated diabetic rats significantly decreased the level of blood glucose, glycosylated hemoglobin as well as increased level of insulin and hemoglobin. The activities of hexokinase, pyruvate kinase, glucose6-phosphate dehydrogenase, glycogen synthase, and glycogen content level were increased to near normal in mangiferin treated diabetic rats. The activities of lactate dehydrogenase, glucose-6-phosphatase, fructose-1,6diphosphatase and glycogen phosphorylase were significantly decreased in liver tissue of diabetic treated rats. These findings demonstrated that mangiferin possess antidiabetic activity against STZ-induced diabetic rats. The antidiabetic effect of mangiferin was compared with standard antidiabetic drug glibenclamide.

Characterization of a thermostable alkaline protease produced by marine Streptomyces fungicidicus MML1614

Abstract: Totally 191 different marine actinomycetes were isolated from 256 different marine samples collected from the Bay of Bengal and its associated Pulicat lake and Pichavaram mangrove, India. Among them, 157 produced caseinase, 113 produced gelatinase and 108 produced both the protease enzymes. An isolate coded as MML1614 was selected for further study as it exhibited high proteolytic activity. The MML1614 was identified as Streptomyces fungicidicus based on polyphasic taxonomical approach including 16S rRNA sequence analysis. The culture conditions were standardized for the growth and protease production in S. fungicidicus MML1614. The protease was isolated from a 6-day-old culture filtrate of S. fungicidicus MML1614 and partially purified up to 4.5-fold. The protease was optimally active at pH 9 and 40 °C and it was stable up to pH 11 and 60 °C. PMSF and NaCl inhibited the enzyme activity up to 22 and 11%, respectively. The partially purified protease removed the blood stain more effectively when combined with different detergents than the detergents alone.

Proteomic analysis of cytoplasmic and surface proteins from yeast cells, hyphae, and biofilms of Candida albicans.

Abstract: Candida albicans is a human commensal and opportunistic pathogen that participates in biofilm formation on host surfaces and also on medical devices. We used DIGE analysis to assess the cytoplasmic and non-covalently attached cell surface proteins in biofilm formed on polymethylmethacrylate and planktonic yeast cells and hyphae. Of the 1490 proteins spots from cytoplasmic and 580 protein spots from the surface extracts analyzed, 265 and 108 were differentially abundant respectively (≥1.5 fold, p<0.05). Differences of both greater and lesser abundance were found between biofilms and both planktonic conditions as well as between yeast cells and hyphae. The identity of 114 cytoplasmic and 80 surface protein spots determined represented 73 and 25 unique proteins respectively. Analyses showed that yeast cells differed most in cytoplasmic profiling while biofilms differed most in surface profiling. Several processes and functions were significantly affected by the differentially abundant cytoplasmic proteins. Particularly noted were many of the enzymes of respiratory and fermentative pentose and glucose metabolism, folate interconversions and proteins associated with oxidative and stress response functions, host response, and multi-organism interaction. The differential abundance of cytoplasmic and surface proteins demonstrated that sessile and planktonic organisms have a unique profile.

Dual responsive chemosensors for anion and cation: Synthesis and studies of selective chemosensor for F― and Cu(II) ions

Abstract: New colorimetric chemosensors, 1-[2-{(4-nitrobenzylidene)amino}phenyl]-3-phenylthiourea ( 1 ), 1-[2-{(2-hydroxy-5-nitrobenzylidene)amino}phenyl]-3-phenyl thiourea ( 2 ) have been synthesized and characterized by spectroscopic techniques and XRD. The molecular structure of receptor 1 was determined by X-ray crystallography and it has the triclinic space group P 1 with cell parameters a = 7.2705 A (6), b = 11.0178 A (9) c = 12.0137 (9) A and Z = 2. Anion binding studies carried out using 1 H NMR and UV–visible spectrophotometric titrations revealed that these receptors exhibit selective recognition towards F − over other halide anions. The selectivity for F − among the halides is attributed mainly to the hydrogen-bond interaction of the receptor with F − . Receptors 1 and 2 (5 × 10 −5 M) show color change from colorless to brown and yellow respectively in the presence of tetrabutylammonium fluoride (TBAF, 5 × 10 −3 M). Moreover, F − -induced color changes remain the same even in the presence of large excess of Cl − , Br − , and I − . Chromogenic receptors 1 and 2 undergo distinct color changes from colorless to violet ( 1 ) or bluish green ( 2 ) on gradual addition of Cu(II) and can be used as colorimetric probes for spectrophotometric and visual analysis of Cu(II) in the presence of other transition metal ions such as Mn 2+ , Co 2+ , Ni 2+ and Zn 2+ . The binding constant for 2 was found to be higher than that for 1 towards F − and Cu(II) ion and this may be due to presence of OH group in 2 , which offers extra binding site.

Silymarin inhibited proliferation and induced apoptosis in hepatic cancer cells

Abstract: Objectives: The aim of this study was to investigate mechanisms involved in the growth inhibitory effect of silymarin, in humanhepatocellular carcinoma. Materials and Methods: The human hepatocellular carcinoma cell line HepG2 was utilized and the MTT assay was performed to study the antiproliferative effect of silymarin. Dual staining was undertaken for ethidium bromide/acridine orange, propidium iodide staining and DNA fragmentation studies were executed to confirm the presence of apoptosis. Cell-cycle analysis was revealed by flow cytometry and mitochondrial transmembrane potential was measured by uptake of the mitochondrial-specific lipophilic cationic dye rhodamine 123. Western blotting analysis for cytochrome c, p53, Bax, Bcl-2, APAF-1, caspase-3, survivin, β-catenin, cyclin D1, c-Myc and PCNA was carried out. Results: Silymarin inhibited population growth of the hepatocellular carcinoma cells in a dose-dependent manner, and the percentage of apoptotic cells was increased after treatment with 50 and 75 µg/ml silymarin for 24 h. Silymarin treatment increased the proportion of cells with reduced DNA content (sub-G0/G1 or A0 peak), indicative of apoptosis with loss of cells in the G1 phase. Silymarin also decreased mitochondrial transmembrane potential of the cells, thereby increasing levels of cytosolic cytochrome c while up-regulating expression of pro-apoptotic proteins (such as p53, Bax, APAF-1 and caspase-3) with concomitant decrease in anti-apoptotic proteins (Bcl-2 and survivin) and proliferation-associated proteins (β-catenin, cyclin D1, c-Myc and PCNA). Conclusions: Our results demonstrate that silymarin treatment inhibited proliferation and induced apoptosis in the human hepatocellular carcinoma cell line HepG2.

Ursolic acid attenuates oxidative stress-mediated hepatocellular carcinoma induction by diethylnitrosamine in male Wistar rats.

Abstract: Hepatocellular carcinoma is the most common primary cancer of the liver in Asian countries. For more than a decade natural dietary agents including fruits, vegetables and spices have drawn a great deal of attention in the prevention of diseases, preferably cancer. Ursolic acid is a natural triterpenoid widely found in food, medicinal herbs, apple peel and other products it has been extensively studied for its anticancer and antioxidant properties. The purpose of this study was to evaluate the effect of ursolic acid in diethylnitrosamine (DEN) induced and phenobarbital promoted hepatocarcinogenesis in male Wistar rats. Antioxidant status was assessed by alterations in level of lipid peroxides and protein carbonyls. Damage to plasma membranes was assessed by levels of membrane and tissue ATPases. Liver tissue was homogenized and utilized for estimation of lipid peroxides, protein carbonyls and glycoproteins. Anticoagulated blood was utilized for erythrocyte membrane isolation. Oral administration of UA 20 mg/kg bodyweight for 6 weeks decreased the levels of lipid peroxides and protein carbonyls at a significance of p< 0.05. Activities of membrane and tissue ATPases returned to normal after UA administration. Levels of glycoproteins were also restored after treatment. Histopathological observations were recorded. The findings from the above study suggest the effectiveness of UA in reducing the oxidative stress mediated changes in liver of rats. Since UA has been found to be a potent antioxidant, it can be suggested as an excellent chemopreventive agent in overcoming diseases like cancer which are mediated by free radicals.